Process and apparatus for purifying or dressing clay



Oct. 28, 1941.

PROCESS L. GERECHT 2,260,776 AND APPARATUS FOR PURIFYING OR DRESSING CLAY A Filed Sept. 12, 1938 2 Sheets-Sheet 1 0 fij'i.

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PROCESS AND APPARATUS FOR PURIFYING OR DRESSING CLAY Fi'led Sept. 12, 1938 2 Sheets-Sheet 2 Patented Oct. 28, 1941 NIT D STATES PATENT OFFICE PROCESS AND APPARATUS FOR PURIFYING on DRESSING CLAY Ludwig Gerecht, Kassel, Germany Application September 12, 1938, Serial No. 229,610 In Germany May 4, 1937 9 Claims. (Cl. 233-27).

The process of this invention is characterised in that moist masses of clay are introduced into a centrifuge and subjected therein to centrifugal action- The speed of rotation of the centrifuge is so adjusted that the requisite separation of the fragmentary or coarse and heavy impurities, takes place and at the same time the clay mass is disintegrated, thoroughly impregnated'with' moisture and homogenised.

According to this invention it has been unexpectedly found that a moist clay mass permeated by fragmentary or coarse and heavy impurities behaves verysimilarly in a centrifuge to a sushigher up the container walls and finally discharges over the edge of the container.

The coarse constituents collect in the lower part of the centrifuge, where the fragmentary clay particles become softened. It is only necessary to ensure that the residual stones and the like can be removed continuously or at intervals.

In addition to the coarse and heavy impurities the clay masses also contain impurities of other kinds, for example roots and the like. According to this invention it has been found that these impurities also may be easily removed by pressing the clay mass by the action of the centrifugal force through a grating-like device or grid. The upper end of the container of the centrifuge is for example provided with a gratng. through which the clay, creeping up the walls of the container, must pass beforeit leaves the container. Preferably the proportion of clay and water or the moisture content of the clay being charged pension of solid particles in a liquid and that it is merely necessary suitably to adjust the speed of rotation of the centrifuge and the-moisture content of the clay mass, in order to effect separation, on the one hand into moist clay and, on the other hand into fragmentary or coarse and heavy impurities. According to this invention it has been further found that during this centrifuge treatment the clay mass is simultaneous 1y disintegrated, thoroughly impregnated with :moisture and homogenised. The water intro-,

duced together with the clay is in a very short time pressed into the claymass;

It crude clay and water are introduced into a centrifuge and this centrifuge is set in rotation the entire contents of the centrifuge are pressed "ainst the walls of the container, the coarse and heavy impurities collecting in the lower parts it the walls of the container, whilst the clay. articles and water creep up the walls of the ontainer as further clay masses are introduced. n the first stage the clay mass disposed near the walls of the container contains less water than the clay mass disposed nearer the middle of the centrifuge. On introducing fresh clay into the rotating centrifuge, the fresh mass of clay to the centrifuge is so adjusted, that the mass shows a greater softness than would be necessary for a plastic moulding. But the proportion 'of water shall be smaller thanfor preparing a liquid slip.

A preferred embodiment of apparatus accord- .ing to this invention consists of a centrifuge,

the lower part of which is constructed in the form of a cylinder or a'truncated cone and the upper'part of which consists of a disc of relatively large diameter. lower part in the form of a trlmcated cone is in general to be preferred, since this construction ensures that the coarse and heavy impurities will be conveyed downwards and outwards,

entire centrifuge or the upper part thereof in ahousing, against the walls of which the clay mass is pressed into the layer rich in water and is there very emciently and thoroughly impregnated with moisture, as a result of which a layerpoor in water and a layer rich in water are again formed, this being repeated at each fresh intro duction of clay. During the further operation of the centrifuge the clay mass constantly creeps flung out of the centrifuge strikes. The container is for exampleso constructed that the walls approach in a downward direction after the manner of a funnel and a screw conveyor or other conveying means, which continuously removes the clay masses continuously discharging from the centrifuge and falling down into the funnel-like container, is provided at the lower end of the funnel.

The construction of the One or more inclined centrifuge plates may also be mounted on the upper disc.

The material under treatment is with advantage introduced as near the middle of the rotating centrifuge as possible, a feed hopper, the lower outlet of which extends to the lower part of the cylinder; or truncated cone of the centrifuge, being for example disposed round the upper end of the vertical central shaft.

In the preferred embodiment of apparatus having a lower cylindrical or truncated cone part and an upper disc, the grating-like device for intercepting roots and the like preferably consists of a slotted ring mounted on the upper disc.

The upper disc may also be entirely or partially constructed in the form of a filter or sieve. The lateral bounding surfaces of the disc are preferably constructed in the form of a filter or sieve, because it has proved to be advantageous for separating the coarse and heavy impurities to treat a clay mass which contains a higher percentage of moisture than is necessary or advisable for directly further working up the clay in presses. Owing to the construction of the lateral bounding surfaces of the disc in the form of a filter, the

disc is with advantage of larger diameter than the lower part of the centrifuge, the pressure with which the clay mass is pressed against the filter surface is very considerable and thereby enables the desired separation of the water to be eflected. The construction of the surface of the disc itself as a filter also promotes this action. It is advantageous to return the water, which passes through the filter surface, by means of channels disposed below the filter to the lower part of the centrifuge in order to promote the disintegration and separation of the clay mass.

It has also proved to be advisable, on starting the centrifuge, to place fine grained to powdery non-swelling substances, such as brick-dust, sand or the like, on the upper disc up to the point of discharge over the upper discharge plate, whereby the filtering action is promoted.

fication of the centrifuge, only the left part being represented,

Fig. 4 shows a construction of the centrifuge with vacuum arrangement,

Fig. 5 is a part section of the lower part. The centrifuge consists of a container which revolves about the central shaft 0. The drive of clay mass is freed by the action of centrifugal Y force from a part of the water. Since the upper this central shaft, which may be effected from below or above by gear-wheels or bevel-wheels by direct belt drive or by means of 8. directly coupled electric motor, is not shown in the drawings. The centrifuge container consists of a truncated cone part b, which is continued downwards in the cylindrical part c. The enlarged container d is connected to the bottom of this cylindrical part c and is closed round its upper end by removable plates e. The bottom of the container is closed by the disc f.

The disc 0 which is provided laterally with two cated cone portion 1). A slotted ring In is disposed on the disc 9. The material under treatment is introduced through the feed hopper I, which is continued in a cylindrical part m. The struts connecting the individual parts of the container with the central shaft are shown at n, m, m and n3.

o and p are the upper and lower bearings respectively of the central shaft.

The centrifuge plates 71. are preferably constructed in the form of filtering surfaces and for this purpose are provided with a number of fine. meshed sieves. In the embodiment illustrated in the drawings two centrifuge plates are provided for the purpose of effecting further separation of the mass under treatment on the upper disc. If desired, a cover q may be disposed between the centrifuge plates h and i in order to retain any further coarse particles contained in the mass.

This cover also may be removable. The cen-' trifuge plate i'for this purpose with advantage projects, for example for about 2 cms., at an acute angle into the disc.

The disc surface 0 may likewise be composed of grids or sieves. A casing may if desired be disposed round the centrifuge plates h and i and below the disc g, which casing returns the water, which passes through at'this point, into the lower part of the centrifuge (e. g. at c). This casing is not illustrated in the accompanying drawings.

The entire centrifuge is disposed within a housing 1', the bottom of which is funnel-shaped. At the lower end of the funnel a screw conveyor s is provided for removing the purified or dressed material collecting at this point. n are doors in the container 1'.

In Fig. 2 an embodiment of the upper part of the. centrifuge is shown, in which the slotted ring k is arranged at an angle on the upper disc, nearly parallel to the centrifuge plate h. The slotted ring I: is covered by an annular plate t for preventing a throwing out of the clay-mass over the slotted ring. The mass shall pass the slotted ring 70. Preferably this slotted ring or grid k is made relatively dense, i. e. the gaps between the individual ring-rods are narrow for removing small pieces and impurities from the clay mass.

Below the slotted ring 10 the housing of the centrifuge is arranged in an angle, nearly in the same angle as the slotted ring. The angle of this part may also be greater or smaller, but it is advisable to avoid stops. The sloping surface is upwardly covered by flaps u. These flaps are segments of a circle round the axis of the centrifuge and are movable around joints extending along chords of the said circle. The flaps u are preferably so arranged and have such a weight, that they are shut during the course of the centrifuge, are opened by the pressure of the clay mass, but

remain shut against pressure of water coming lar masses may be arranged so that the more heavy clay prevents a passing through of water whilethe water is forced to-pass in upward direction into an annular container (not shown in the drawings) from which it may be conducted into an annular channel or into the lower part of the centrifuge.

It is advisable tolengthen the feed hopper in downward direction.- According to Fig. 3 an arcentrifuge plates 71. and i is mounted on the trun 7 rangement of tines w sloping upwards in the direction of rotation can be provided above or, in

the upper part of the feed hopper, this resulting in a stronger downward pulling of the fed matethat the water added to the clay for the decomposition is held back in the inner part of the centrifuge and consequently this part can be 10.

kept closed at the top. With this object in view rods 1 are fixed on the shaft in the upper part on the-funnel and can rise under the action of the centrifugal force and form a complete closure at the top, but on the other hand, owing to their yieldability, allow the passage of the -material thrown in. The liquid splashed up in the inner part during the centrifuging is thrown back by this closing wall formed by the rods and the air current.

On the lower end of the funnel a ring-shaped closing wall 2 is fitted which extends, into close proximity of the closure wall set for example at anangle in the drawings. It serves to hold back the liquid clayv layers in the lower part of the centrifuge. Theselayers, according to the operation described, can only creep up the outer wall in narrow layers so that they are less moist.

The same object is attained, according to the modified form of construction of this lower part of the centrifuge illustrated in Fig; 5, by a vertical grid 2a, which is intended to guide downwards large hard components, and by plates 2b;

intended to' assist in forcing upwards the sprayed water by stronger air movement.

The novel centrifuging process may be assisted by de-aerating the clay. Accordingly, as shown in Fig. 4, the centrifuging part proper, namely the rims h and i are constructed as vacuum chamber. This vacuum chamber II is located outside the grid It. It is closed on the inner side by the inclined ring-shaped walls l2, l3 and by the flaps l4, l5. These flaps are loaded and have packing coverings causing a closureas long as they are not raised by the clay mass passing therethrough. The suction takes place through the pipes IS. The de-aeration enables a further separation of water, and 'a thickening of the purified clay. Annular slot l1 conducts off the ing. The container of the centrifuge is provided v with ribbed pipes which are heated by steam or these latter also force the upwardly creeping clay They are lined on the inner side with waterproof,

packing material such as rubber, so that they do not allow the passage of water. Owing to the pressure of'the following clay masses" the water is compelled-to move inwards and is centrifuged or flung out higher upby the water centrifuging plate 4.

The clay mass which has forced its way through the flaps 3 arrives at the grid k which is closed at the top by a ring disc t (Fig. 2). In

. this space small stones are held back which, if necessary, are removed from above.

The clay which-has passed through the grid encounters in the rings h and i alternating inelined and vertical annular discs I and 8 which force it to move outwards along a zig-zag path and cause additional working through. Thus, water is again separated from the clay mass and flung out in upward direction. The upper rim is covered by guide plates 9 for preventing the water from re-entering the centrifuge. The

water thrown out at the points 4 and under the plates 9 is conducted upwards and outwards and discharged downwards through casings 9a, 9b here provided.

hung out here.

' The annularapertures It, It in the plate a are water like the flaps 3. The suction conduit extends upwards along the shaft. .The throwing out is effected upwards through the flaps l5.

Finally. heat may be' added to assist the dress- The clay mass under treatment and'the requi- Y site quantity of water (as ascertained by preliminary tests) are continuously or periodically introduced through the feed hopper 1. Brickdust is at the same time placed on the disc g. The centrifuge is set in rotation as soonas the container has been filled with clay mass up to about the upper edge'of the cylindrical part 0. Further quantities of claymass and water are introduced during the rotation o f the centrifuge through the feed hopper l at such a speed that the upper level of the centrifuge contents at the central shaft does not rise during the rotation of the centrifuge above the cylindrical lower part of the centrifuge;

Stones and the like collect during the rotation of the centrifuge in the lowest portion thereof and the clay mass freed therefrom creeps up the walls of the truncated cone part b in accordance with the further amounts of clay mass introduced and arrives on the disc y, where it is freed from roots and the like by passing through the slotted ring it. The clay mass is then freed from water on the disc by being pressed against the centrifuge plate h and finally passes over the centrifuge plates into the container surrounding the centrifuge, whereit falls down into the con- The casing 9b is perforated at the height of the rim 1, so that the clay can be veyor screw.

The operation in the case of the special conticity, a centrifugal force in a downwardly expanded centrifuge, whereby specifically heavier constituents, stones, and the like. are extracted at the bottom, and applying to the remainder of the mass a homogenizing treatment during the centrifugal action as it passes upwardly in the centrifuge, said homogenizing action including passing said mass through restricted passages. which separates lighter constituents, roots, and.

the like from the mass.

2. A process according to claim 6 in which the first rendering of th clay mass is accomplished by adding water to the clay in such amounts as to cause the mass to assume a state softer than a plastic moldable mass but of considerably greater consistency than fluid.

3. A process according to claim 6, in which heat is applied to the clay mass for the purpose of controlling the amount of moisture therein.

4. A process for the preparation of clay comprising, applying, to a mass of crude clay of such moisture content as to be in a state of plasticity, a centrifugal force in a downwardly expanded centrifuge, whereby specifically heavier constituents, stones, and the like, are extracted at the bottom, applying to the remainder of the mass a. homogenizing treatment during the centrifugal action as it passes upwardly in the centrifuge, and subjecting the clay mass to a vacuum during the centrifugal action and after the heavier constituents have been removed.

5. A process for the preparation of clay comprising, applying, to a mass of crude clay of such moisture content as to be in a state of soft plasticity, a centrifugal force in a downwardly expanded centrifuge, whereby specifically heavier constituents, stones and the like, are extracted at the bottom, applying to the remainder of the mass a homogenizing treatment during the centrifugal action as it passes upwardly in the centrifuge, and contacting said mass of clay.during the latter stages of the centrifuging with a finely divided non-inspissating substance.

6. A process for the preparation of clay. comupwardly in the centrifuge, and discharging the purified clay paste from the upper portion of the centrifuge.

7. Centrifugal apparatus for the preparation of clay, comprising a downwardly expanded centrifuge in the form of a truncated cone, said centrifuge being mounted for rotation about a centrally disposed vertical axis, said centrifuge having a centrally disposed filling opening at the upper end, and discharge openings at the bot- '-tom communicating directly with the lower portion of said centrifuge for coarse, heavier foreign constituents removed from the mass of clay during operation of the apparatus, an annular plate secured at the upper end of said truncated cone to receive a clay mass from the apparatus after the heavy constituents have been removed therefrom, and an annular grating disposed adjacent the overflow of the apparatus and in the path of the clay being treated for removing roots and upper end, and discharge openings at the bottom communicating directly with the lower portion of said centrifuge for coarse, heavier foreign constituents removed from the mass of clay during operation of the apparatus, an annular plate secured at the upper end of said truncated cone to receive a clay mass from the apparatus after the heavy constituents have been removed therefrom, the upper edge of said cone being provided with a short, outwardly and upwardly disposed annular flange, an,annular grating disposed above said flange in the path of the clay, and a plurality of segment-shaped flaps disposed between the flange and the grating and in the path of the clay and mounted for opening under the pressure of the ascending clay mass.

9. Centrifugal apparatus for the preparation of clay, comprising a downwardly expanded centrifuge in the form of a truncated cone, said centrifuge being mounted for rotation about a centrally disposed vertical axis, said centrifuge having a centrally disposed filling opening at the upper end, and discharge openings at the bottom communicating directly with the lower portion of said centrifuge for coarse, heavier foreign constituents remove from the mass of clay during operation of the apparatus, an annular plate secured at the upp r end of said truncated cone to receive a clay mass from the apparatus after the heavy constituents have been removed therefrom, a plurality of annular chambers mounted on said annular plate, a passage connecting said chambers with a vacuum, said chambers having openings therein, and valvelike flaps disposed in said openings and operable to open under the action of the clay mass during operation of the apparatus.

LU'DWIG GERECHT. 

